Full beam discharge headlight with two power levels

ABSTRACT

A method for controlling the full-beam headlights of automotive vehicles, particularly cars, which headlights are provided with dischargeable light sources. The light source (2) is chosen so that when supplying the light source with its nominal power it will produce a luminous flux which greatly exceeds the luminous flux that is standard for full-beam lighting, supplying the light source (2) with a lower power causes the light source (2) to produce a luminous flux which is normal for full-beam lighting. A power level selection (7; 10, 4) is provided for enabling the light source (2) to be supplied selectively with the lower power or with its nominal power.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and to an arrangement forcontrolling the headlights of automotive vehicles, and in particular carheadlights.

2. Description of the Related Art

The design of modern cars in which the front part of the car dips makesit difficult to fit extra lights effectively. Extra lights impair theappearance of the car, constitute a greater accident risk to unprotectedroad users and make the car more difficult to wash. Extra lights alsoimpair the aerodynamics of the car and have a negative effect on enginecooling, since they are normally fitted in front of the engine radiator.

There is a significant need to improve full-beam lighting for certaincategories of drivers who drive in certain regions, and particularlywith respect to certain markets, even though conventional headlightswill satisfy many users.

It has become progressively more usual for car owners to replacestandard bulbs in existing headlamps with bulbs of greater power, inorder to obtain more powerful full beam lighting. However, bulbs ofgreater power damage the reflectors, by changing the reflectance of thereflectors as a result of higher temperature in the headlamp. The highertemperature can even deform the reflectors, resulting in a distortedlight image.

Furthermore, a more powerful bulb has the drawback of necessitating thatthe driver dip the lights earlier when driving in the dark on a typicalroad with repeated encounters with oncoming traffic interspersed with aclear road ahead, so as not to dazzle the drivers of oncoming traffic,as opposed to the case when using a standard bulb. This means that thedriver's eyes must constantly become accustomed to strong light, i.e.when the lights are on full beam, and a much weaker, dipped light, wheredipped lighting is used over a longer distance to prevent dazzling ofoncoming traffic. This drawback is the reason why drivers do notnormally have extra lights, such as long-distance lighting, switched-onwhen driving along roads on which oncoming vehicles are frequentlyencountered, therewith requiring the lights to be dipped repeatedly.

This problem is solved in accordance with the present invention byproviding weak headlights for certain situations while eliminating theaforesaid drawback and, at the same time, eliminating the need of extralighting.

SUMMARY OF THE INVENTION

The present invention thus relates to a method of controlling thefull-beam lighting of automotive vehicles, particularly for cars,wherein the headlights are provided with light sources of adischargeable type. The light source is chosen so that when suppliedwith its nominal or rated power, it will produce a luminous flux whichgreatly exceeds the normal luminous flux of full-beam lighting. In orderto obtain a luminous flux which is normal for full-beam lighting, thelight source is supplied with lower power; and means are provided forselectively supplying the light source with said lower power or with itsnominal power.

The invention also relates to a control arrangement for carrying out themethod.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to anexemplifying embodiment thereof and with reference to the accompanyingdrawings, in which

FIG. 1 illustrates schematically a headlamp and associated power means;and

FIG. 2 illustrates a light switch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an arrangement for controlling the full beamheadlights of automotive vehicles, particularly cars, wherein headlight1 is provided with light sources 2 of a dischargeable kind. Thereference numeral 3 in FIG. 1 identifies the headlight reflector. Suchlight sources are available commercially and marketed, among others, byPHILIPS under the trade name MICRO POWER-LIGHT.

Such light sources 2 are powered by a power means 4 which applies analternating voltage across the light source. The voltage applied isnormally a square-wave voltage. Such power means are also known andavailable commercially.

When applied to a car or to some other automotive vehicle, the powermeans 4 is connected to the vehicle electrical system by cables 5, 6which supply the power means with direct current voltage.

According to the invention, the light source 2 is designed to produce aluminous flux which greatly exceeds the normal luminous flux offull-beam lighting when supplied with its nominal power. According tothe invention, the power means 4 is designed to supply the light source2 with lower power when in a first position, such as to emit from theheadlight 1 a full beam having a luminous flux which is normal for afull beam. Also provided is a means 7 with which the power means 4 canbe switched selectively from said first position to a second position inwhich the power means supplies the light source 2 with its nominalpower.

According to one preferred embodiment of the invention, this lower poweris between 40% and 70% of the nominal or rated power, preferably about50%.

A full beam will normally have a luminous flux of 1,500 lumens forinstance. This means that a preferred embodiment of the light sourcewill generate a luminous flux of 3,000 lumens at nominal power.

According to one preferred embodiment of the invention, there is used adischarge lamp of the aforesaid kind having a nominal power of 35 Watts.In the case of standard head-lights, this light source will produce aluminous flux of 3,000 lumens when supplied with its nominal power. Whensupplied with a power of 18 Watts, the light source will produce aluminous flux of 1,500 lumens.

Conventional full-beam headlights, i.e. a headlight which emits afull-beam lobe, will generate a normal luminous flux when the lightsource is supplied with a power of 18 Watts. This means that when thelight source is supplied with a power of 35 Watts, the light emitted bythe headlight will correspond to a normal full beam in combination witha conventional long-distance headlight, because of the higher luminousflux. Such long-distance headlights are normally fitted to the vehicleas extra lighting.

According to one preferred embodiment of the invention, the means 7includes a driver-operated switch, by means of which the power means canbe switched between two said positions.

The switch is connected by means of a cable 8 to an appropriate knowncontrol circuit not shown which is conveniently integrated with thepower means and which functions to control the power output of saidpower means by voltage-regulating the output voltage and/or outputcurrent of the power means.

When the driver alternates between full beam and dipped beam in a normalmanner, the beam will be switched between dipped lighting with apredetermined luminous flux given by the light source for dippedlighting and a full beam with the lower power input when the switch isin its first position, i.e. a full beam with normal luminous flux. Whenthe switch is in its second position, the vehicle lighting will beswitched between said dipped lighting and a full beam lighting havingthe higher power input, i.e. lighting which corresponds to normalfull-beam lighting in combination with long-distance lighting. Thisembodiment can be applied irrespective of whether the dipped-beamheadlights and the full-beam headlights are mutually separate orintegrated in one and the same headlamp unit.

The switch may be an integral part of the normal light switch in a caror some other automotive vehicle. FIG. 2 illustrates an example of onesuch light switch 9.

The reference numeral 10 identifies automatic activation of the vehiclelights when the vehicle is started, for instance activation of thevehicle side lights and dipped/full beam lighting. All lights areswitched off in position 11. A position light or the like is ignited inposition 12.

Normal dipped lighting and normal full-beam lighting are activated inposition 13. This enables the power means to drive the light source 2 atthe lower power input. The driver alternates between dipped beam andfull beam with the standard full beam switch, normally a lever placed onthe steering wheel.

Standard dipped lighting with the stronger full-beam lighting isactivated in position 14. This enables the power means to drive thelight source 2 at its nominal power input. The driver alternates betweendipped lighting and full-beam lighting with the aid of the standardfull-beam switch.

Thus, the present invention obviates the need to fit extra lighting tothe vehicle while still obtaining, when desired, the quality of lightthat an extra light would provide.

This eliminates the problems mentioned in the introduction. Although theinvention has been described above with reference to a number ofexemplifying embodiments thereof, it will be understood thatmodifications can be made. For instance, it is conceivable to includemore than two power positions. Furthermore, light sources with othernominal power inputs can be chosen. The switch means 7 can also beconstructed as a separate switch means. Furthermore, the invention maybe applied to only one of the vehicle headlights or to both headlights.It is also conceivable to utilize the invention in the aforedescribedmanner but in conjunction with a full-beam headlight which is alsoconstructed for dipped lighting.

The present invention is not therefore limited to the described andillustrated embodiments thereof, since variations and modifications canbe made within the scope of the following claims.

What is claimed is:
 1. A method for controlling the full-beam headlightsof an automotive vehicle, said method comprising the steps of:providinga power source that is operable to provide power at each of a first,nominal power level and a second power level that is a lower power levelthan the first power level; providing a headlight that includes adischarge lamp light source that is operable at two different powerlevels and that emits full-beam luminous flux at a first full-beam fluxlevel when the light source is provided with electrical power at thefirst, nominal power level, and that emits full-beam luminous flux at asecond full-beam flux level that is lower than the first full-beam fluxlevel when the light source is provided with electrical power at thesecond power level; providing a power level selector switch that isswitchable between a first position corresponding with the first powerlevel and a second position corresponding with the second power level toselectively control the level of power applied by the power source tothe light source; operating the power level selector switch between thefirst switch position to provide electrical power to the light source atthe first power level to cause the light source to provide full-beamlight at the first full-beam flux level, and the second switch positionto provide electrical power to the light source at the second powerlevel to cause the light source to provide full-beam light at the secondluminous flux level, wherein the first full-beam flux level is greaterthan the second full-beam flux level; and providing a beam selectorswitch for selectively operating the headlight at one of a full-beamposition and a dipped-beam position, wherein the full-beam position ofthe beam selector switch provides full-beam light from the light sourceat a luminous flux level that is dependent upon the position of thepower level selector switch, and wherein the dipped-beam position of thebeam selector switch provides light at a predetermined dipped-beamluminous flux level that is the same level for each of the first andsecond positions of the power level selector switch.
 2. A methodaccording to claim 1, wherein the second power level is between about40% and about 70% of the first power level.
 3. A method according toclaim 1, wherein the power level selector switch is included as a partof a light switch provided for controlling the operation of exteriorlights of the vehicle.
 4. A method according to claim 1, wherein thesecond power level is about 50% of the first power level.
 5. Anarrangement for controlling the light intensity of full-beam headlightsof automotive vehicles, said arrangement comprising:a headlight having adischarge lamp light source wherein the headlight emits full-beamluminous flux at a first full-beam flux level when the light source isprovided with electrical power at a first, nominal power level, and thatemits full-beam luminous flux at a second full-beam flux level that islower than the first full-beam flux level when the light source isprovided with electrical power at a second power level lower than thefirst power level; a power source electrically connected with theheadlight to supply an alternating voltage across the light source,wherein the power source is operable to provide power at each of afirst, nominal power level and a second power level that is a lowerpower level than the first power level; a power level selector switchfor selectively controlling the level of power applied to the lightsource, wherein the power level selector switch is operable between afirst switch position that provides electrical power to the light sourceat the first power level to cause the light source to provide full-beamlight at the first full-beam flux level, and a second switch positionthat provides electrical power to the light source at the second powerlevel to cause the light source to provide full-beam light at the secondluminous flux level, wherein the first full-beam flux level is greaterthan the second full-beam flux level; and a beam selector switch forselectively operating the light source at one of a full-beam positionand a dipped-beam position, wherein the full-beam position of the beamselector switch provides light from the light source at a luminous fluxlevel that is dependent upon the position of the power level selectorswitch, and wherein the dipped-beam position of the beam selector switchprovides light at a predetermined uniform dipped-beam luminous fluxlevel for each of the first and second positions of the power levelselector switch.
 6. An arrangement according to claim 5, wherein thesecond power level is between about 40% and about 70% of the first powerlevel.
 7. An arrangement according to claim 5, wherein the second powerlevel is about 50% of the first power level.